Spectroscopy and chemistry of MgNC, NaH, and NaOH on ice surfaces

To date, observations and studies of metal-containing compounds have been restricted to the gas phase. In this work I primarily characterized the spectra and chemistry of magnesium isocyanide (MgNC) on amorphous ice surfaces as modelled with density functional theory cluster calculations. MgNC, the first metal-containing molecule detected in interstellar space, is a reactive radical with a mixture of covalent and ionic bonding between Mg and NC. The mid-IR spectra of MgNC-nH₂O and (MgNC-nH₂O)⁺ exhibit the characteristic features of water ice as well as the CN stretch. Once deposited on an ice surface, hydrogen atoms can react facilely with adsorbed MgNC to form HMgNC, a known astromolecule; there is sufficient energy to eject HMgNC into the gas phase. Acetylene (HCCH) and hydrogen cyanide (HCN) reactions with adsorbed MgNC were also characterized. While there are barriers to forming complexes in both cases, they appear to be submerged below the reactant asymptote. Subsequent reactions of H with these complexes can form larger Mg-containing compounds but also offer catalytic pathways to the formation of the vinyl radical (C₂H₃) from HCCH and the methaniminyl radical (H₂CN) from HCN. Unlike MgNC, NaH and NaOH are both observed to react with water in ice, with solvent-coordinated Na⁺ and OH^- produced from both Na-containing compounds.